We wrote our own Asset Loader before ResourceLoader came along, so we need to merge some of the features before we can switch back to the core loader. I think the main ones are support for sass processing, javascript minification and a different strategy for dynamic asset loading of “mixed” bundles of javascript,css, messages and unprocessed templates (Mustache). We also found performance improvements from a different approach to bundling assets, and we wanted a framework that had more explicit support for different skins (desktop/mobile/app) with filtering.